Andrzej Ambroziak

Investigations of underwater FHPP for welding steel overlap joints

Friction Hydro Pillar Processing (FHPP) is one of the most innovative friction welding processes. FHPP can be used under water whereby it can be employed to repair marine structures or undersea oil pipelines. Every new technique requires testing and further development and in the present case this was made possible by the PIPETAP research project sponsored by the European Community. The main idea of PIPETAP is to develop an advanced hot tapping system for operations on undersea deep-water oil and gas pipelines [ 1 ]. The system will also improve the safety and reduce the cost of onshore hot tapping operations. This report presents experimental work on a FHPP welding system, focusing on sleeve welds.

Using resistance spot welding for joining aluminium elements in automotive industry

The aluminium alloys are more frequently used in automotive industry especially as an alternative material for car-bodies. In this article the comprehensive summary concerning technology of resistance spot welding of aluminium alloys was presented. The welding schedules, electric parameters of welding, electrodes materials and electrodes life time by resistance spot welding aluminium were described. Few examples directly from automotive industry were presented and advantages of aluminium as a material for some vehicle parts were also discussed.

Friction Welding of Aluminium and Aluminium Alloys with Steel

The paper presents our actual knowledge and experience in joining dissimilar materials with the use of friction welding method. The joints of aluminium and aluminium alloys with the different types of steel were studied. The structural effects occurring during the welding process were described. The mechanical properties using, for example, (i) microhardness measurements, (ii) tensile tests, (iii) bending tests, and (iv) shearing tests were determined. In order to obtain high-quality joints the influence of different configurations of the process such as (i) changing the geometry of bonding surface, (ii) using the interlayer, or (iii) heat treatment was analyzed. Finally, the issues related to the selection of optimal parameters of friction welding process were also investigated.

Real-time ultrasonic control of spot-welded steel joints

Resistance welding is a welding method where the joining of materials is achieved by heating the contact area of the pieces to be joined with an electric current and pressure from plastic strain in the area of the weld. The process of heating workpieces in resistance welding occurs as a result of heat generated by the resistance of the welding current running through the workpieces. Spot welding is a process of joining overlapping workpieces between electrodes, which clamp the pieces together and pass the welding current on to heat the contact area (or ‘spot’) to the proper welding temperature (above the melting temperature). Because this process is quick, simple and effective, spot-welded joints are commonly applied in the automotive industry. Although the welds are usually made at robotized welding stations, they may still show some defects. Fundamental factors having a negative effect on spotwelded joints include:

Ultrasonic quality control methods for spot-welded joints

Spot resistance welding is the most popular method of connecting the steel structures of automotive vehicles. At a time when quality requirements relating to finished goods are higher and higher, welded joints must undergo precise controls in order to assure the highest safety standards possible. Ultrasonic methods enable quick and accurate assessment of any welded joints quality, and at the same time are environmentally friendly. Three ultrasonic applications that make it possible to determine the quality of a welded joint were discussed in the article: testing of joints welded by a single welding head, scanning acoustic tomography, and the resistance spot welding analyzers system – with the application of a mosaic head. The advantages and drawbacks of individual systems were described based on our own experience.

Testing of thin-walled steel joints fabricated by spot welding and plug welding

Selected methods of joining which can be used for manufacturing and repairing of car bodies by means of welding are presented in this article. Three kinds of 1 mm-thick steel sheets were used in the tests: deep drawing steel (DC04) and two-phase steels of increased high strength (DP600 and DP800). The comparative connections were carried out by means of resistance spot welding and with plug joints made by means of the MAG method and through braze welding. Comparative assessment of the strength and geometrical parameters of the test joints was then conducted.

IN‐LINE ULTRASONIC INVESTIGATION OF SPOT WELD QUALITY USING MULTI‐TRANSDUCER SET‐UP

This article presents one of the most recent developments in real‐time ultrasonic quality control methods for resistance spot welds. Currently existing in‐line systems use single‐element transducer to characterize the spot weld quality. The new set‐up is based on 8 ultrasonic transducers placed in one line above the center of the spot weld. The solution presented in this paper makes another step forward towards improvement of accuracy of measurements using array of ultrasonic transducers.

Investigations of the friction welding of Incoloy MA 956 alloy

Friction welded similar material (work hardened and thermally treated) alloy Incoloy MA 956 joints and Incoloy MA 956 alloy/austenitic steel X10CrNiTi 189 joints were tested. The microstructures, microhardness and tensile strength of the joints were determined. Optimum friction welding process parameters were matched. Friction welding has been found to be useful for joining Incoloy MA 956 alloys together and for joining the latter with austenitic steel X10CrNiTi 189.

A comparison of microstructure and of thermal transport properties of yttria and ceria stabilized zirconia coatings deposited by suspension plasma spraying

The single cathode plasma torch SG-100 was used to spray suspension prepared with the use of two kinds of commercial powders ZrO2+8 wt. % Y2O3 (8YSZ) and ZrO2 + 24 wt.% CeO2 + 2.5 wt.% Y2O3 (24CeYSZ). The suspensions were formulated using finely milled solid phase, water and ethanol. The operational spray parameters being the same for each powder were modified by changing: (i) spray distance; and (ii) torch scan linear speed. The coatings microstructures were analyzed with the use of optical and scanning electron microscopes as well as by X-ray diffraction. Their porosities were found with help of the image analysis of metallographically prepared cross-sections. Thermal diffusivity was measured with the use of commercial system LFA 447 NanoFlash® working at the temperatures limited to 300°C. The measurements were made with the use of the coatings sprayed on the steel substrate and a 2-layers numerical model was applied to determine thermal diffusity of the coatings. The obtained data were used to calculate thermal conductivity of stabilized zirconia coatings.

Coat spraying with use of the cold spray method

In this article, physical phenomena accompanying the process of cold spraying as well as principles of bonding particles with a surface were analysed. Moreover, the basic process parameters as well as the construction of actual spraying devices were shown. Numerous advantages of the method and its applications in the industry were presented.